2026 GMC Sierra 1500 Owner Complaints

2026 Denali, 6.2, failed after getting off express way while on my way for a fishing get away and pulling my boat. NO warning lights, noises, nothing. Came to a stop sign and at the last second slammed into park. Dash went black, 10 seconds later would come back on and try to start, then the dash goes black. Sheriff pulled up 20 or so minutes later and told my wife to get back into the vehicle as she was directing semis and other cars to go around. Towed to a chevy dealership 13 miles away. After Running tests on the truck, came up blown engine. 7600 miles. 5 hours later we left with a loaner and able to continue on with our plans. I do thank the dealership for their help and loaner. 23 business days later they delivered my truck to my house and returned in the loaner. After all my investigating on these engines, I will not be buying another one. Time for GM to invest some of their profits into finding the problem!

NHTSA ID

11755712

Incident

Jul 6, 2026

Driving on the highway near Rockport, WA, when vehicle suddenly loss propulsion, engine light appeared, and vehicle went into transport mode enabled. Without causing an accident, I was able to pull to the side of the road. Once I put vehicle in park, it shut off and displayed, “Tranport Mode On. Vehicle would not start and was towed home. My son-in-law was able to disable transport mode, but vehicle still will not start. Will notify dealership on Monday.

NHTSA ID

11755699

Incident

Aug 8, 2026

Driving on the highway near Rockport, WA, when vehicle suddenly loss propulsion, engine light appeared, and vehicle went into transport mode enabled. Without causing an accident, I was able to pull to the side of the road. Once I put vehicle in park, it shut off and displayed, “Tranport Mode On. Vehicle would not start and was towed home. My son-in-law was able to disable transport mode, but vehicle still will not start. Will notify dealership on Monday.

NHTSA ID

11755698

Incident

Aug 8, 2026

I have a 2026 GMC Sierra 1500 with the 6.2L engine. I purchased it on [XXX]. On [XXX] with 13,000 miles on the truck the engine started making a bad noise from the lower end of the motor. I immediately took it to the dealer Randy Wise Buick GMC in Fenton Michigan. They diagnosed it as a spun bearing and had to replace the engine. I just got it back today August 7th 2026 INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11755572

Incident

Jul 24, 2026

The contact owns a 2026 GMC Sierra 1500. The contact stated that while her husband was driving approximately 10 MPH, the vehicle unexpectedly shut off and independently shifted into park(P). The contact stated that previously, while the vehicle was idling in a parking lot, with air conditioner activated, the Auto START/STOP feature engaged, and the vehicle shut off. The message “Service Transmission” was displayed. The vehicle was taken to a local dealer and was diagnosed with transmission failure. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage was approximately 2,000.

NHTSA ID

11755200

Incident

Aug 4, 2026

Mileage

2,000 mi

I am submitting this complaint to report what I believe is a serious safety-related defect involving the General Motors 6.2L L87 V8 engine installed in my 2026 GMC Sierra Denali. On July 10, 2026, while driving on a public highway near Bogata, Texas, the engine suddenly began making severe mechanical noises before catastrophically failing without warning. The engine seized completely while the vehicle was in motion. At the time of failure, the truck had only 13,517 miles. The sudden loss of engine power left my wife and me stranded on the roadside. Had this occurred while crossing an intersection, merging into traffic, passing another vehicle, towing a trailer, or traveling in heavier traffic, the consequences could have been far more serious.

NHTSA ID

11755053

Incident

Jul 10, 2026

I was driving on 96 W. in slow traffic on the freeway when the vehicle put itself in neutral and shut off

NHTSA ID

11754782

Incident

Aug 4, 2026

Engine died while driving at higher speed on interstate. Barely able to pull to emergency lane before truck stopped. No warning of any issues with it. Had towed to dealership. Dealership confirmed 6.2 engine was faulty. Engine replaced under warranty. Truck only had 1207 miles on it when engine died.

NHTSA ID

11753938

Incident

May 8, 2026

6.2 l just blew up per dealership

NHTSA ID

11753614

Incident

Jul 29, 2026

While traveling from [XXX] to [XXX] for vacation, I was in [XXX], and when I pulled off the interstate and came to a stop sign the vehicle quit. At first, I was unable to restart the Vehicle, but after sometime I got it started and was able to pull it off the road while the engine was making very loud clattering noise and the vehicle would not stay running. Prior to this there were no warning, lights or indications that the engine was going to quit. I checked the engine oil and it was full. I had the vehicle transported to a GMC dealer in [XXX], where it was diagnosed as requiring a new engine. The vehicle is a 2026 GMC Sierra 1500 Denali purchased in December 2025 and has 8,865 miles on it. A little over 4000 miles I had the vehicle oil changed at Starling GMC Titusville Fl. At the time of my service visit, I asked the service writer, [XXX] to check the engine idle because at times it seemed to run a little rough and it quit while pulling in my driveway one day. [XXX] advised me that there is no idle adjustment on the vehicle, so I said I’ll just keep an eye on it. There were never any indications of an engine problem prior to this or even as of now there are no warnings displayed on the instrument panel. I also subscribe to onstar and it indicates everything in the vehicle is normal with no issues. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11753455

Incident

Jul 17, 2026

The telematics module for the OnStar system continues to stop working, I have had this truck in a dealership service center multiple times for them to reset the system (instead of replacing the defective parts). Along with the infotainment system not working properly (cuts in and out, blinks on/off, delay in actions) Doors unlock while driving, front/rear cameras come on when I stopping at an intersection, I have given them documentation of the diagnostic reports from dealerships

NHTSA ID

11753107

Incident

Dec 28, 2025

6 month old, 9,000 miles 2026 Sierra 1500 with Duramax 3 liter suffered an engine control module failure 4 hours into a 12.5 hour drive home from family vacation. First a transmission service warning flashed, then an emissions system failure with a forced speed reduction warning. This happened with two children and a dog in the vehicle. OnStar did diagnotics and said I had to see a dealer. Fortunately one was nearby and they determined the engine control module needed to be replaced--but i was 8.5 hours' drive from home with kids and dog and would have had to stay for 2-4 days awaiting parts and repair. I traded the truck at the dealer for a new vehicle and drove that home. This was a major safety concern traveling with children and a dog on a nearly 100 degree day. And it was a brand new vehicle.

NHTSA ID

11752717

Incident

Jul 22, 2026

When going up my 5% grade driveway the truck has slammed into “park” while moving two times. The car turns off as it slams into park and a “ service transmission” warning is on the dash. It leaves small skid marks from doing this while moving. It has 1790 miles on it. Dealer has had it a week and says they cannot duplicate the issue. Google search seems to indicate many trucks have had the same issues going up an incline.

NHTSA ID

11752469

Incident

Jul 23, 2026

I bought the truck with 2 miles , shut off on me within 1,300 miles wouldn’t turn on , supposedly it was a bad fuse that was burned out , Second time it shut off on me again , all my sensors were going off and on and truck wouldn’t turn back on , they told me they couldn’t figure out the problem evaczue they had disconnected the battery and it erased all the codes 3rd time , they changed my oil and they forgot to torque the screw back correctly and all the oil spilled and cost my engine to lock up and mess up , they replaced the motor with a new one 4th time , supposedly it needs a replacement for a catalytic converter which is being replaced now as we speak or sometime this week

NHTSA ID

11751712

Incident

Jun 30, 2026

I purchased this new full-size heavy-duty pickup, and at purchase the selling dealer installed a 3-inch suspension lift kit with 37-inch tires on 22-inch wheels as a paid dealer upfit. The lift kit manufacturer publishes a maximum tire size of 35 inches on a 20-inch wheel for this kit; the tires and wheels the dealer installed exceed that spec. The lift manufacturer confirmed directly that they would never approve exceeding the 35-inch tire / 20-inch wheel recommendation. The dealer's assistant manager confirmed that NO calibrations of any kind were performed after the lift and 37-inch tires were installed, and said nothing is recalibrated when a lift is done with 37-inch tires. This vehicle is factory-equipped with forward collision alert, automatic emergency braking, front pedestrian braking, lane departure warning, and automatic high-beam control. These crash-avoidance systems rely on forward-facing camera and sensor aim, which depends on ride height and suspension geometry. A 3-inch lift with 37-inch tires materially changes that geometry. With no calibration performed, there is no assurance these safety systems are aimed or functioning to spec. The truck was also never aligned after the lift and the tires are cupping. The headlights were never re-aimed for the higher ride height, and the speedometer was never recalibrated and reads inaccurately. The oversized tires also contact the body. The left front tire has torn into the front fender, the fender well is misaligned, and it is forcing the lower front edge of the driver's door out of alignment. The dealer's only proposed remedy is to keep cutting the fender wells; the trimming already done has exposed electrical wiring behind the wheel well to mud, water, and road debris. I am reporting this because the assistant manager's statement suggests it may be the dealer's standing practice—other customers may be driving lifted trucks with uncalibrated crash-avoidance systems without knowing it.

NHTSA ID

11750542

Incident

Jun 23, 2026

While driving vehicle the engine lost power and shut off in traffic. There were no warning signs of issues at that time. The dashboard went blank and then reappeared and the truck was in park. after that the truck would not shift gears. The truck was towed to the dealership and found to have had catastrophic engine failure.

NHTSA ID

11749941

Incident

Jul 3, 2026

My 2026 GMC Sierra has an oil-canned roof from a touchless car wash because the sheet metal lacks structural rigidity. This caused the roof to buckle and caused a permanent fold in the roof of the truck. There is already documented issues for this exact problem on the newer GMC Canyons and Chevrolet Colorado mid-sized trucks. Bulletin for reference NHTSA Official TSB #23-NA-209 PDF. I leased the vehicle on 6/19/2026 and this happened on approximately 7/7/2026. The vehicle only has 1,480 miles on it as of this date.

NHTSA ID

11749108

Incident

Jul 7, 2026

No sound at different times. No way to reset issue. TSB issued May 14, 2026 for known issue. As of July 6, no estimate on repair. Blinkers make no sounds, Onstar can call but you cannot hear them. In event of accident, no communication.

NHTSA ID

11748779

Incident

Jul 1, 2026

Sudden catastrophic engine failure with only 6000 miles on vehicle on May 26, 2026. 2026 GMC Sierra 1500 AT4X with known defective 6.2L L87 V8. Had to coast across three lanes of traffic to get to other median as highway location was on large curve. Someone very easily could have been hurt or killed.

NHTSA ID

11748047

Incident

May 26, 2026

I bought my 2026 GMC in April. Several times the audio doesn't work work. When this happens audio related safety technology is affected too including turn signal sounds and back camera audio also. A person walking behind the truck can be seen on the screen but no warning beeps are heard. When backing up the warning for getting too close to an object also doesn't work. I called the dealer in early May and was told that this was a known issue and that it needed a software update. took the truck to the dealer on May 8th and the software update was performed. When the update had been completed when I started the truck after the update there was no audio. I told the service advisor it was currently happening and she took it back to the technician. They disconnected the battery cables to reset the system and told me to do that in the future until the issue is resolved. I opened Case #100978480 with GM on June 1st because I wanted to be sure that GM was also informed of the issue. I was hoping they would be proactive and report back to me what they were doing to resolve this issue. Instead I was told that I need to call the dealer and the dealer would call GM because an update might be available but dealers wouldn't be informed and wouldn't check unless I called.

NHTSA ID

11747094

Incident

Jun 28, 2026

My motor has a catastrophic failure. Started sputtering and Squealing.

NHTSA ID

11746991

Incident

Jun 26, 2026

In early June 2026 I discovered a sheared pin on the front control arm of my 2026 GMC Sierra 1500 AT4X (VIN [XXX]), sold to me new by Parks GMC, Kernersville NC, with a dealer-installed Performance Package modifying the factory suspension. I delivered the truck to Parks GMC for warranty repair. The dealer represented it as a 1-2 day job. The truck was out of service approximately 2 weeks. The dealer sub-contracted the work to a third-party shop (CCV). At pickup, the dealer provided written documentation stating the repair was NOT PERFORMED. Neither the dealer nor I has been able to obtain any documentation from CCV describing what, if anything, was actually done to the vehicle. THREE UNRESOLVED SAFETY CONDITIONS: SHEARED FRONT CONTROL ARM PIN — original failure, status of repair unknown and undocumented. TIRE-TO-BODYWORK CONTACT — front tires intermittently rub the inside of the wheel wells during normal driving and steering, causing visible damage to the plastic mud guards. Tire-to-bodywork contact creates risk of sidewall failure, sudden air loss, and loss of vehicle control. FRONT RIGHT SUSPENSION CREAK — loud, persistent creak from the front right suspension during low-speed driving and steering inputs. Present at service drop-off, never addressed. Consistent with a worn, loose, or improperly installed suspension component. I escalated to Parks GMC management and GMC Customer Assistance. Parks has not provided a written repair plan, no decision-maker has contacted me, and the only response has been "looking into it." GMC Customer Assistance declined to assign a District Service Manager. I am filing to document these suspension and tire safety conditions in the federal database against this VIN and to request NHTSA evaluation of whether further action is warranted. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11746601

Incident

Jun 1, 2026

2026 GMC Sierra 1500 AT4X with 3898 miles. Driving 71mph on state highway on flat grade road. Lost power and vehicle shut down after pulling off the road. No previous lights or warning signs prior to power loss. Vehicle would not start afterwards. OnStar Diagnostics sent ECM Engine and Transmission System code P0016. Had vehicle towed 100miles to GM dealership. Upon inspection of vehicle, the Service Department contacted me the following day and said the the vehicle needed an entire engine replacement according to GM cooperate. I asked if it had anything to do with the 6.2L V8 L87 engine problems from previous recall years of 2021-2024. Service tech stated yes it was more than likely the same issue. Very unhappy with my new GM vehicle purchase. Will have to have a full engine replacement BEFORE my first oil change!

NHTSA ID

11746541

Incident

Jun 24, 2026

I was driving on interstate 95 at approximately 70 to 75 mph when I lost all power and compromise steering with tractor trailer behind me God willing I was able to pull over to the shoulder. My safety was compromised and I lost all faith in Gmc. My vehicle has been out of service for 27 days at this point while waiting for an engine replacement with no ETA on service. According to Pennsylvania lemon law after 30 days a lemon law claim can be submitted

NHTSA ID

11744121

Incident

May 19, 2026

The contact owns a 2026 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, there was an abnormally loud and rough knocking sound coming from the engine block. The oil pressure decreased to zero, and the engine seized. There was no warning light illuminated before or after the failure. The vehicle was towed to a dealer, where it was diagnosed with a blown engine. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was 5,018.

NHTSA ID

11743279

Incident

Apr 2, 2026

Mileage

5,018 mi